Sister And Mom Fist Fought

So let me explain. One day my sister(14) came home. To my mother's home and she had an attitude. She went to her room and from my understanding the day before she didn't do her chores of sweeping the steps and our mother took her phone because of her attitude and the chore not being done. Somehow they had words and my mother went into my sister's room and began to slap her and hit her hard in the head.

My sister started to scream telling my mother to stop hitting her. They separated. My sister tried to steal her phone away. My mother caught on. More words were exchanged. They somehow ended up downstairs. My mother slapping my little sister and hitting her. My sister "fought" back by pushing and kicking our mother.

My mother somehow ended up on top of my sister sitting on her. My sister calling her a bitch, stank, a fat whore. Telling her to shut the fuck up. My mother continuing to slap her in the head. My sister has heart problems and asthma and I was trying to get my mother off. I believe she went to far as to sit on her but how do you feel about it?